From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753271Ab3EKF5T (ORCPT ); Sat, 11 May 2013 01:57:19 -0400 Received: from blu0-omc3-s24.blu0.hotmail.com ([65.55.116.99]:28314 "EHLO blu0-omc3-s24.blu0.hotmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752531Ab3EKF5H convert rfc822-to-8bit (ORCPT ); Sat, 11 May 2013 01:57:07 -0400 X-EIP: [Nv6ezajNYWqT2nM4VQMoxjfgwCVkclbC] X-Originating-Email: [yuhongbao_386@hotmail.com] Message-ID: From: Yuhong Bao To: "mingo@kernel.org" , "linux-tip-commits@vger.kernel.org" CC: "linux-kernel@vger.kernel.org" , "hpa@zytor.com" , "fernando@oss.ntt.co.jp" , "tglx@linutronix.de" , "hpa@linux.intel.com" Subject: RE: [tip:x86/urgent] x86-64, init: Do not set NX bits on non-NX capable hardware Date: Fri, 10 May 2013 22:57:06 -0700 Importance: Normal In-Reply-To: References: <1367476850.5660.2.camel@nexus>, Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT MIME-Version: 1.0 X-OriginalArrivalTime: 11 May 2013 05:57:06.0345 (UTC) FILETIME=[5DF84990:01CE4E0C] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (resending as plaintext) > During early init, we would incorrectly set the NX bit even if the NX > feature was not supported. Instead, only set this bit if NX is > actually available and enabled. We already do very early detection of > the NX bit to enable it in EFER, this simply extends this detection to > the early page table mask. AFAIK the only production x86-64 processor that don't support NX that I know of is the original Nocona D0 stepping. Must more common are the problem of BIOSes disabling the NX feature. Yuhong Bao